What Glacial Feature Is Circled In Figure 1

What Glacial Feature is Circled in Figure 1? A Comprehensive Guide to Glacial Landforms

(Note: Since I cannot see "Figure 1," I will provide a comprehensive explanation of various glacial features. You can then apply this knowledge to identify the feature in your image. Please provide the image if you would like a specific answer.)

Glaciers, immense rivers of ice, are powerful forces of nature capable of sculpting dramatic landscapes. As they move, they erode, transport, and deposit vast amounts of material, leaving behind a distinctive array of landforms. Understanding these landforms is crucial for interpreting past glacial activity and predicting future changes in glacial environments. This article explores a range of glacial features, providing the knowledge you need to identify the circled feature in your Figure 1.

Erosional Glacial Landforms: Sculpting the Landscape

Glaciers are effective agents of erosion, carving out impressive features through several processes including abrasion (the scraping of rock against rock) and plucking (the lifting and removal of rock fragments). Key erosional landforms include:

1. Cirques:

• Definition: Bowl-shaped depressions formed at the head of a glacier, typically on mountainsides. They are carved by erosion from the glacier's headwall, where freeze-thaw weathering and plucking are particularly effective.
• Characteristics: Steep, often concave walls, a relatively flat floor, and frequently contain a tarn (a small lake) after the glacier melts.
• Identification: Look for a bowl-shaped hollow nestled in a mountain range, often with a steep back wall and a relatively flat bottom.

2. Arêtes:

• Definition: Sharp, knife-like ridges formed between two adjacent cirques or valleys eroded by glaciers. They represent the remnants of the interfluve (the area between two valleys) after significant glacial erosion.
• Characteristics: Narrow, jagged, and often extend for significant lengths. They are prominent features in alpine landscapes.
• Identification: Look for thin, sharp ridges separating valleys, often with steep sides.

3. Horns:

• Definition: Pyramid-shaped peaks formed when several cirques erode back into a mountain from different directions.
• Characteristics: Steep, pointed summits, typically found in areas with significant glacial activity. The Matterhorn is a classic example.
• Identification: Look for sharp, pointed peaks surrounded by cirques and arêtes.

4. U-shaped Valleys (Glacial Troughs):

• Definition: Wide, deep valleys with a characteristic U-shape, carved by glacial erosion. They contrast sharply with the V-shaped valleys formed by rivers.
• Characteristics: Steep, straight sides, a flat or gently sloping floor. Often contain features like hanging valleys and truncated spurs.
• Identification: Look for wide, U-shaped valleys, particularly in mountainous regions.

5. Hanging Valleys:

• Definition: Smaller valleys that join a larger glacial valley at a significantly higher elevation. They are formed because smaller tributary glaciers erode less deeply than the main glacier.
• Characteristics: They join the main valley at a sharp angle, often resulting in waterfalls.
• Identification: Look for smaller valleys that "hang" above a larger, more deeply incised valley.

6. Truncated Spurs:

• Definition: Triangular-shaped features formed when a glacier erodes the sides of a valley, removing the projecting spurs of land that extend into the valley.
• Characteristics: These are often very sharp and angular.
• Identification: Look for triangular shapes cut off abruptly from valley sides.

Depositional Glacial Landforms: Leaving Their Mark

As glaciers melt, they deposit the sediment they have transported, creating a variety of landforms. These deposits, collectively known as glacial drift, can be classified as either till (unsorted sediment deposited directly by the glacier) or outwash (sorted sediment deposited by meltwater streams).

1. Moraines:

• Definition: Ridges or mounds of till deposited by a glacier. Different types of moraines indicate different stages of glacial advance and retreat.
• Types: Lateral moraines (along the sides of a glacier), medial moraines (formed by the merging of two lateral moraines), terminal moraines (at the glacier's furthest extent), and recessional moraines (formed during periods of glacial retreat).
• Characteristics: Unsorted, often composed of a mixture of rock fragments of various sizes. Can form significant ridges.
• Identification: Look for long, linear ridges of unsorted sediment, often parallel to the former glacier's path.

2. Drumlins:

• Definition: Elongated, oval-shaped hills of till, typically aligned parallel to the direction of ice flow. Their formation is still debated, but likely involves the streamlining of pre-existing sediment by glacial ice.
• Characteristics: Asymmetrical profile, with a steeper stoss side (facing the direction of ice flow) and a gentler lee side (opposite the ice flow).
• Identification: Look for elongated hills with a characteristic asymmetrical shape, often clustered together in fields.

3. Eskers:

• Definition: Long, winding ridges of sand and gravel deposited by meltwater streams flowing within or beneath a glacier.
• Characteristics: Often sinuous in shape, composed of well-sorted sediment.
• Identification: Look for long, meandering ridges of sand and gravel, often running parallel to the former glacier's path.

4. Kames:

• Definition: Mounds or hills of stratified sand and gravel deposited by meltwater streams on or near the surface of a glacier.
• Characteristics: Conical or irregular in shape, composed of well-sorted sediment.
• Identification: Look for mounds or hills of sand and gravel, often with a stratified structure.

5. Kettle Lakes:

• Definition: Depressions formed by the melting of large blocks of ice buried within glacial deposits.
• Characteristics: Typically irregular in shape and filled with water.
• Identification: Look for small, often irregular lakes, especially in areas with glacial deposits.

6. Outwash Plains:

• Definition: Extensive, flat plains composed of stratified sand and gravel deposited by meltwater streams flowing away from a glacier.
• Characteristics: Relatively flat topography, composed of well-sorted sediment.
• Identification: Look for wide, flat plains of sand and gravel, often found downstream of glacial deposits.

Identifying the Glacial Feature in Figure 1: A Step-by-Step Approach

To accurately identify the glacial feature circled in Figure 1, follow these steps:

1. Examine the Image: Carefully observe the shape, size, and surrounding features of the circled area.

2. Consider the Context: Where is the feature located? Is it in a mountainous region, a flat plain, or a valley?

3. Assess the Sediment: Is the sediment sorted or unsorted? This helps differentiate between glacial till and outwash deposits.

4. Analyze the Shape: Is it a linear ridge, an elongated hill, a bowl-shaped depression, a sharp peak, or something else entirely?

5. Compare to Descriptions: Refer back to the descriptions of the various glacial features discussed above and match the characteristics of the circled area to those descriptions.

6. Eliminate Possibilities: Systematically eliminate features that don't match the image's characteristics.

By following this systematic approach, you will be well-equipped to identify the circled glacial feature and demonstrate a strong understanding of glacial geomorphology. Remember, the key is to pay close attention to the details of the image and use the provided information to reach a confident conclusion. Providing the image would allow for a precise identification.